An ocean of trouble

Dylan Tussel, The Columbus Dispatch

Sunday

Aug 14, 2011 at 12:01 AMAug 14, 2011 at 11:38 AM

Every time she enters the elaborate coral lab in New Albany, Andrea Grottoli travels through time and space. A few steps take her to an ocean in 2050. A few more, and she is in the water in 2100. At either point in time, Grottoli doesn't much like the view. The Ohio State University ocean researcher has set up rows of tanks to observe how coral reefs will fare over time under different conditions.

Every time she enters the elaborate coral lab in New Albany, Andrea Grottoli travels through time and space.

A few steps take her to an ocean in 2050. A few more, and she is in the water in 2100. At either point in time, Grottoli doesn’t much like the view. The Ohio State University ocean researcher has set up rows of tanks to observe how coral reefs will fare over time under different conditions.

“You see increasing amounts of coral disease.” By 2050, she estimates,60 percent of the world’s coral could be dead.

Why is this important? Coral reefs are home to 25 percent of all marine species. The algae that grow among them are a main source of food for many species.

Reefs also serve as buffers between coastal regions and severe storms. Places including the Florida Keys, Hawaii and the Virgin Islands depend on reefs to protect them from hurricanes, said Mark Eakin, coordinator of the National Oceanic and Atmospheric Association’s Coral Reef Watch.

Fishing, farming and even washing cars affect reefs. Phosphorus from soaps and fertilizers washes into the ocean and causes coral to “bleach,” or expel the algae that provide vital nutrients and color.

“As the temperature has been going up … we’ve been seeing a major increase in the amount of coral-bleaching,” Eakin said. “It’s been affecting reefs even in remote locations where the coral is well-protected.”

Burning fossil fuels contributes as well. The carbon dioxide released into the air is absorbed into the ocean where it becomes carbonic acid. This increase in acidity has been shown to interfere with coral’s ability to calcify, or grow its skeleton.

Coral lives on a calcium carbonate skeleton, which dissolves in acids, said Michael Webster, executive director of the Coral Reef Alliance, a California-based conservation group.

“What happens is, when you (increase the acidity) of the ocean, coral has a hard time building and maintaining that skeleton,” he said.

Calcification is vital to coral, but by 2100, the process will have slowed significantly, Grottoli said.

“The combination of reduced calcification and reduced health, we think, will be a lot worse than just one or the other,” she said.

The worst-case scenario, Webster said, has already been observed during historical periods of climate change.

“We could make the environment inhospitable to coral,” he said. “Reefs could disappear.”

Grottoli created her lab at Reef Systems Coral Farm, which grows and sells coral.

She set up three carbon-dioxide experiments: one that mimics current conditions; another that represents conditions in 2050; and a third for 2100.

In each experiment, half the coral is kept in healthy temperatures, and the other half lives in warmer water, replicating a stressful effect of climate change.

Certain species of coral are more resilient than others, Grottoli said. And some appear to be unaffected by acidity.

“If you add both (warmer temperatures and acidity), then are there any species of coral that will be resilient?” Grottoli said. “Will they be able to survive it?”

The three-year study will look at four species of coral that were placed in treatment tanks on July 19.

Two weeks into the four-week observation, a species called Acropora millepora, which is found throughout the Pacific and Indian oceans and the Red Sea, had retracted its tentacles in the year-2100 tanks.

Corals use their tentacles to feed, Grottoli said, so these Acroporas likely had stopped eating. Bleaching also was visible in some.

Corals of the same species, living in current conditions, had extended tentacles, but showed some bleaching.

Three weeks in, researchers have measured decreases in photosynthesis efficiency in Acropora when carbon dioxide and heat levels were raised.

Both are stress responses, Grottoli said.

Much of coral’s energy comes from photosynthesis in the algae. When algae disappear, coral relies more on their other main source of food — plankton. To replicate this, researchers feed brine shrimp to the coral every three nights.

Most coral, however, cannot survive on this type of food alone and burns through fat reserves. Grottoli said they also might slow their metabolism, something that has not been documented.

Throughout the experiment, researchers will measure factors that indicate the health of the coral, such as the rates of calcification and photosynthesis, and how changes in the water’s acidity affect the acidity of coral tissue.

One of her hypotheses is that higher internal acidity can slow calcification in some species of coral.

After the experiments end, the research team will kill the corals and measure health factors such as energy reserves and stress proteins.

The second phase of the experiment will involve repeating the first setup while controlling for nutrients — nitrogen and phosphorus — present in the water around populated coastal regions.

In small doses, nutrients can stimulate coral growth. Anything larger, however, can be detrimental to the animal’s health.

The $1 million project was funded through a National Science Foundation grant.

dtussel@dispatch.com

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